[AMRadio] 6146A's Arrived (was DX-100B on Phone - bad audio distortion / oscillation)

[Gerald Stockinger]

Rick, I have been following your tale of woe for a bit and this morning I
looked up a copy of the scheme of your rig. I could not find one for the
DX100B only the DX100. The first thing I see is the DX100 did not have
nuetralizing of the 6146's. That may have been added for the B version. The
thing I would try in any event is to replace the 1300pf screen bypass caps
for the finals. Use a good quality low inductance cap like a centralab door
knob no.850 type if you can get them. If the screen of a tube like the 6146
is not tied securely to ground for RF it will not be stable. Good luck. 73

Gerald D. (Jerry) Stockinger
K9GOZ

On Tue, Dec 6, 2011 at 11:03 PM, Rick Poole <wa1rkt at arrl.net> wrote:

> Well, the 6146A's arrived today, to replace the 6146B's in my DX-100
> which are suspected of causing my spur / self-oscillation problem.
>
> I bought four of them (I could use a couple of spares for my KWM-2A
> anyway) and took the two that matched most closely on my TV-7D and
> put those in.
>
> No joy... self-oscillation is as bad as ever.  Tried several
> positionings of the neutralization wand and then removed the
> neutralization wand altogether... still no joy.
>
> So, I got the XYL to help me wrestle the thing over to the workbench
> (feed me the line cord through the back of the cabinet and then move
> the cabinet out of the way), whereupon my Simpson 260 fell on her
> foot, so she is not happy... :-(
>
> But it's now out of the cabinet and ready for me to start going over
> it from front to back and try to figure out what's happening.  Stay
> tuned...
>
> Rick WA1RKT
>
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